WO2019163197A1

WO2019163197A1 - Light-emitting module

Info

Publication number: WO2019163197A1
Application number: PCT/JP2018/038790
Authority: WO
Inventors: 力山崎
Original assignee: 株式会社村田製作所
Priority date: 2018-02-20
Filing date: 2018-10-18
Publication date: 2019-08-29
Also published as: CN111566881A; JPWO2019163197A1; US11799265B2; JP7010361B2; US20200321750A1

Abstract

This light-emitting module (1) is provided with a substrate (2), a surface light-emitting element (3), and an optical waveguide (5). An array-type surface light-emitting element (3) has a plurality of light sources (3A), and is mounted on the substrate (2). The optical waveguide (5) is mounted on the surface light-emitting element (3) in a state in which the optical waveguide (5) covers the plurality of light sources (3A). The optical waveguide (5) has a refractive index distribution with respect to the radial direction and extends in the axial direction. The optical waveguide (5) condenses a plurality of rays (R) emitted from the surface light-emitting element (3).

Description

Light emitting module

The present invention relates to a light emitting module that emits light.

Patent Document 1 describes a fiber lens including a multimode pigtail fiber and a refractive lens. In this fiber lens, light from a light source such as a laser diode can be condensed on a focused spot by a refractive lens, and efficient optical coupling is possible.

Special table 2007-507007

By the way, the fiber lens described in Patent Document 1 connects a refractive lens and a multimode pigtail fiber. However, the refractive lens needs to be formed in, for example, a hyperbola shape or an approximate hyperbola shape, and the manufacturing cost tends to increase. Further, since the refractive lens and the multimode pigtail fiber need to be sufficiently accurately aligned, there is a problem that it is difficult to connect them. In addition, the fiber lens described in Patent Document 1 uses a multimode pigtail fiber to make light incident on the refractive lens or the GRIN lens. For this reason, the overall shape tends to be larger than when light is directly incident on the lens.

The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a light emitting module that can be miniaturized and can output high-intensity light.

In order to solve the above-described problems, a light emitting module of the present invention includes a substrate, an array-type surface light emitting element provided on the substrate and having a plurality of light sources, and covering the plurality of light sources to the surface light emitting element. And an optical waveguide extending in the axial direction with a refractive index distribution with respect to the radial direction, wherein the optical waveguide collects a plurality of light beams emitted from the surface light emitting element.

According to the present invention, downsizing is possible and high-intensity light can be output.

It is sectional drawing which shows the light emitting module by the 1st Embodiment of this invention. It is a perspective view which shows a surface light emitting element. It is sectional drawing which shows the light emitting module by the 2nd Embodiment of this invention.

Hereinafter, a light emitting module according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 show a light emitting module 1 according to a first embodiment of the present invention. The light emitting module 1 includes a substrate 2, a surface light emitting element 3, and an optical waveguide 5.

The substrate 2 is a flat plate formed using an insulating material. As the substrate 2, for example, a printed wiring board or a ceramic substrate is used. The substrate 2 may be a multilayer substrate in which a plurality of electrode layers and insulating layers are alternately stacked. A surface light emitting element 3 is mounted on the front surface 2A (one side main surface) of the substrate 2. An electrode 4 is formed on the back surface 2 B (other main surface) of the substrate 2. The electrode 4 is electrically connected to the surface light emitting element 3. For this reason, a driving current is supplied to the surface light emitting element 3 from the outside through the electrode 4.

The surface light emitting element 3 is formed by, for example, an array type vertical cavity surface emitting laser (VCSEL). The surface light emitting element 3 includes a plurality of (for example, nine) light sources 3A (light emitting portions). These light sources 3A are located on the surface of the surface light emitting element 3 and are arranged in an array of, for example, 3 rows and 3 columns. These light sources 3A emit light together. The light source 3A emits near-infrared light in the 850 nm band, for example. The light source 3 A outputs light (light ray R) along the thickness direction of the surface light emitting element 3. The surface light emitting element 3 is attached to the surface 2A of the substrate 2 by using a bonding method such as wire bonding. Note that the number of light sources 3A included in the surface light emitting element 3 is not limited to nine, and may be two to eight, or may be ten or more. The light source 3A may output light of other wavelengths.

The optical waveguide 5 is formed of a gradient index fiber. The optical waveguide 5 is constituted by an optical fiber made of a resin material having a gradient index core 6. In addition, you may form the optical waveguide 5 using materials other than resin like a glass material, for example.

The optical waveguide 5 includes a core 6 having a high refractive index and a clad 7 having a low refractive index. The optical waveguide 5 is formed in a cylindrical shape. The core 6 is formed in a cylindrical shape and is located at the axial center of the optical waveguide 5. The clad 7 is formed in a cylindrical shape, and is positioned on the outer side in the radial direction of the core 6 and covers the outer peripheral surface of the core 6.

The optical waveguide 5 has a refractive index distribution in the radial direction and extends in the axial direction along the central axis O. Specifically, the refractive index of the core 6 of the optical waveguide 5 is highest at the center position in the radial direction and gradually decreases (for example, in proportion to the square of the radius) toward the outer side in the radial direction. At this time, the axial light ray R incident on the position of the central axis O travels straight along the central axis O inside the optical waveguide 5. On the other hand, the axial light ray R incident on the position shifted from the central axis O propagates in a meandering manner while repeatedly approaching and separating from the central axis O inside the optical waveguide 5. For this reason, the optical waveguide 5 propagates the light incident from the incident end 5A to the output end 5B while repeating condensing and diffusing.

The optical waveguide 5 has a length of about 2 mm to 4 mm with respect to the axial direction. At this time, the optical waveguide 5 is formed with a node portion A where a plurality of light rays R are collected and an antinode portion B where a plurality of light rays R are diffused. The node portions A and the abdominal portions B are alternately arranged along the axial direction. The distance dimension Li between the node portion A and the antinode portion B is determined by, for example, the refractive index distribution in the core 6 and the wavelength of the propagating light. The exit end 5 B of the optical waveguide 5 is a flat surface orthogonal to the axial direction of the optical waveguide 5. In addition, the output end 5B of the optical waveguide 5 is not limited to a flat surface, but may be a hemispherical surface that protrudes in a hemispherical shape toward the outside (emission direction), for example.

Further, the exit end 5B of the optical waveguide 5 is arranged at a position protruding from the nearest antinode portion B by a predetermined protruding dimension Lo. That is, the emission end 5B of the optical waveguide 5 is disposed at a midway position from the antinode portion B to the node portion A. At this time, the protrusion dimension Lo is set to a range (Li / 3 <Lo <Li) that is larger than 1/3 of the interval dimension Li and smaller than the interval dimension Li. Thereby, the light which propagated the optical waveguide 5 is radiate | emitted from the output end 5B in the state which became the condensing tendency. For this reason, the light emitted from the emission end 5B is collected around the emission end 5B to form a spot S.

The optical waveguide 5 is attached to the surface light emitting element 3 using, for example, a joint 8 made of a transparent adhesive. The core 6 has a size that covers all the light sources 3 A of the surface light emitting element 3. For this reason, the light (light ray R) from all the light sources 3 A of the surface light emitting element 3 is incident on the core 6. It is not necessary to precisely align the center of the core 6 and the center of the surface light emitting element 3 as long as light (light ray R) from all the light sources 3A of the surface light emitting element 3 can enter.

The light emitting module 1 according to the first embodiment of the present invention has the above-described configuration, and the operation thereof will be described next.

First, when a driving current is supplied to the surface light emitting element 3 through the electrode 4, a plurality of light sources 3A of the surface light emitting element 3 emit light. These light sources 3 A output light rays R along the thickness direction of the substrate 2. At this time, the output surface (surface) of the surface light emitting element 3 is covered with the optical waveguide 5. For this reason, the light rays R from all the light sources 3 A are incident on the core 6 of the optical waveguide 5. The light beam R incident on the incident end 5 A of the optical waveguide 5 propagates in the axial direction of the optical waveguide 5 while being repeatedly focused and diffused inside the optical waveguide 5. The light propagating through the optical waveguide 5 is emitted from the emission end 5B in a state where the light tends to be condensed. Thereby, the light output from the plurality of light sources 3 A of the surface light emitting element 3 is collected around the emission end 5 B of the optical waveguide 5 to form a spot S.

Thus, in the light emitting module 1 according to the present embodiment, the optical waveguide 5 collects the plurality of light rays R emitted from the surface light emitting element 3. Thereby, since the optical waveguide 5 condenses the plurality of light rays R emitted from the plurality of light sources 3 A of the surface light emitting element 3, high-intensity light can be output from the optical waveguide 5. Further, since the surface light emitting element 3 may be attached to the incident end 5 A of the optical waveguide 5, it is not necessary to use a multimode pigtail unlike the prior art, and the light emitting module 1 can be downsized.

The optical waveguide 5 is constituted by an optical fiber made of a resin material having a gradient index core 6. For this reason, since the freedom degree of refractive index distribution can be raised, the optical waveguide 5 can be formed according to the magnitude | size of the surface emitting element 3. FIG.

Further, the exit end 5B of the optical waveguide 5 is arranged at a position protruding from the nearest antinode portion B by a predetermined protruding dimension Lo. The protrusion dimension Lo is set to a range (Li / 3 <Lo <Li) that is larger than 1/3 of the interval dimension Li from the abdominal part B to the node part A and smaller than the interval dimension Li. Thereby, the light which propagated the optical waveguide 5 is radiate | emitted from the output end 5B in the state which became the condensing tendency. For this reason, the light emitted from the emission end 5B is collected around the emission end 5B to form a spot S.

Next, a second embodiment of the present invention will be described with reference to FIG. The feature of the second embodiment resides in that the optical waveguide has a lens positioned at the light emitting end. Note that in the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

The light emitting module 11 according to the second embodiment includes the substrate 2, the surface light emitting element 3, and the optical waveguide 12 as in the first embodiment. The optical waveguide 12 is formed in the same manner as the optical waveguide 5 according to the first embodiment. For this reason, the optical waveguide 12 includes the core 13 and the clad 14 similar to the core 6 and the clad 7 according to the first embodiment. The surface light emitting element 3 is attached to the incident end 12 A of the optical waveguide 12 by the joint portion 8.

The lens 15 is attached to the emission end 12B of the optical waveguide 12. At this time, the emission end 12 B of the optical waveguide 12 does not need to be a midway position from the antinode portion B of the optical waveguide 12 to the node portion A, and may be positioned at the antinode portion B of the optical waveguide 12. The lens 15 is formed in, for example, a hemispherical shape protruding toward the outside (outgoing direction). At this time, the lens 15 is formed by utilizing the surface tension of the resin material when the molten resin material is attached to the emission end 12 B of the optical waveguide 12. Thereafter, the lens 15 is fixed to the optical waveguide 12 by curing the resin material. The lens 15 is not limited to one formed using surface tension. For example, a separately formed convex lens may be bonded to the emission end 12B of the optical waveguide 12, and a ball lens is attached to the optical waveguide 12 with a jig or the like. You may attach to the output end 12B.

Thus, also in the second embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the first embodiment described above. The optical waveguide 12 has a lens 15 positioned at the light emission end 12B. Thereby, the plurality of light rays R emitted from the plurality of light sources 3 A of the surface light emitting element 3 can be collected by the lens 15. As a result, light can be condensed to the diffraction limit.

It should be noted that the specific numerical values described in the above embodiments are examples, and are not limited to the exemplified values. These numerical values are appropriately set according to, for example, the specification to be applied.

The above embodiments are merely examples, and it is needless to say that partial replacement or combination of the configurations shown in the different embodiments is possible.

Next, the invention included in the above embodiment will be described. The light emitting module of the present invention includes a substrate, an array type surface light emitting element provided on the substrate and having a plurality of light sources, and attached to the surface light emitting element so as to cover the plurality of light sources, and is refracted in a radial direction. An optical waveguide extending in the axial direction with a rate distribution, wherein the optical waveguide condenses a plurality of light beams emitted from the surface light emitting element.

Thereby, since the optical waveguide condenses a plurality of light beams emitted from a plurality of light sources of the surface light emitting element, it is possible to output high intensity light from the optical waveguide. In addition, since the surface light emitting element may be attached to the incident end of the optical waveguide, it is not necessary to use a connector, and the light emitting module can be miniaturized.

In the present invention, the optical waveguide has a lens positioned at an emission end of the light beam. Thereby, the several light ray radiate | emitted from the several light source of a surface emitting element can be condensed with a lens. As a result, light can be condensed to the diffraction limit.

In the present invention, the optical waveguide is constituted by an optical fiber made of a resin material having a gradient index core. Thereby, since the freedom degree of refractive index distribution can be raised, an optical waveguide can be formed according to the magnitude | size of a surface emitting element.

In the present invention, the interval dimension from the antinode portion where a plurality of light rays are diffused to the node portion where the plural light rays are collected is Li, and the projecting dimension from the nearest antinode portion to the emission end of the optical waveguide is Lo. In some cases, the protrusion dimension Lo is set to a value satisfying the relationship Li / 3 <Lo <Li. As a result, the light propagating through the optical waveguide is emitted from the emission end in a state of concentrating. For this reason, the light emitted from the emission end is collected around the emission end to form a spot.

DESCRIPTION OF

SYMBOLS

1,11 Light emitting module 2 Board | substrate 3 Surface light emitting element

3A Light source

5,12

Optical waveguide

5A,

12A Incidence end

5B, 12B Output end 15 Lens

Claims

A substrate,
An array-type surface light-emitting element provided on the substrate and having a plurality of light sources;
An optical waveguide that covers the plurality of light sources and is attached to the surface light emitting element and extends in the axial direction with a refractive index distribution with respect to the radial direction,
The light-emitting module, wherein the optical waveguide condenses a plurality of light beams emitted from the surface light-emitting element.
The light emitting module according to claim 1, wherein the optical waveguide has a lens positioned at an emission end of the light beam.
3. The light emitting module according to claim 1, wherein the optical waveguide is configured by an optical fiber made of a resin material having a gradient index core.
When the interval dimension from the antinode portion where a plurality of light rays are diffused to the node portion where the plurality of light rays are collected is Li, and the protrusion dimension from the nearest antinode portion to the exit end of the optical waveguide is Lo, 4. The light emitting module according to claim 1, wherein the projecting dimension Lo is set to a value satisfying a relationship of Li / 3 <Lo <Li.